The Radeon HD3870 X2 is ATI's biggest video card so far. From left to right: HD3870, Radeon 2900 XT, HD3870 X2, GeForce 8800 GTX. As you can see the card has the exact same length as the NVIDIA GeForce 8800 GTX. The power connector placement is a bit better in my opinion because you dont need any extra space toward the top of the card.
As we all expected, the cooler of the HD 3870 X2 is a dual slot cooling solution. This is necessary to handle the heat output of the two GPUs installed on the card.
The HD 3870 X2 features two DVI outputs which can be used with digital flat panels for resolutions up to 2560x1600. In case you still have an old analog display you can use one of the two included DVI adapters. Of course the card also supports HDMI+HDCP+Audio via the included HDMI adapter. In theory it wuld be possible to design a card with four outputs, each group of two connected to the two GPUs. In order to use all four you would lose CrossFire, so performance would be lower. For certain markets this could still be an interesting product.
Here are the front and the back of the card, high-res versions are also available (front, back). If you choose to use these images for voltmods etc, please include a link back to this site.